R. Thomas · Robert Orr · Robert T. · Robert Thomas · Thomas Orr
| title | ISBN-13 (ISBN-10) | year of publica- tion |
|---|---|---|
| The Animal Kingdom | 978-0-02-593980-6 (0-02-593980-7) | 1965 |
| The Little-Known Pika | 978-0-02-593960-8 (0-02-593960-2) | 1977 |
| Vertebrate Biology | 978-0-03-057959-2 (0-03-057959-7) | 1982 |